Plugs have hitherto been manufactured for this purpose in such a way that the contacts as well as the choke coil needed in the plugs are introduced in the housing. The housing is made, as a rule, of a plastic in a usual manner, and the inner and outer electrical connections to the connection lines are subsequently soldered. A separate chamber with openings toward the interior space of the plug is provided in the plug. The connection wires to be soldered are lead to the poles through these openings. The essential part of the necessary operations, especially of the soldering operations, is performed manually, which requires not only a considerable amount of work, but also a special skill in light of the small size of the parts.